Not sure exactly when your ewes are due? Don't get caught unprepared. Enter your breeding date below to instantly calculate your expected lambing date and likely lambing window.
Sheep commonly range from 142 to 152 days. 147 days is the standard UK average.
Based on a 147-day average gestation. Start preparing your lambing kit and pens before the earliest likely date.
How to calculate lambing dates
Calculating your ewe's due date is straightforward if you know the exact mating or exposure date. The standard sheep gestation period is 147 days (approximately 5 months minus 5 days).
Our sheep gestation calculator adds 147 days to your selected breeding date to provide an estimated lambing date. It also provides a 10-day lambing window (142 to 152 days), as natural variation is very common.
What affects sheep gestation length?
While 147 days is the standard average, several factors can influence exactly when a ewe will lamb:
Breed
Some British sheep breeds, like the Welsh Mountain or Cheviot, may have slightly different averages compared to heavier breeds like the Suffolk or Texel.
Litter size
Ewes carrying multiple lambs (twins or triplets) often lamb a few days earlier than those carrying singles.
Age of the ewe
Older ewes sometimes carry lambs slightly longer than first-time mothers (gimmers/theaves).
Environment
Stress, weather, and diet can subtly impact the exact timing of birth.
Pre-lambing preparation & signs
Because the expected lambing date is an estimate, you should have your lambing kit ready and pens set up at least a week before the earliest date in your lambing window. Good preparation is vital for sheep welfare and a successful lambing season.
Watch for these pre-lambing signs:
- Udder bagging up (enlarging) a few weeks prior.
- Vulva becoming swollen and relaxed.
- The ewe separating herself from the flock.
- Restlessness, pawing at the ground, or nesting behaviour.
- A hollow appearance in the flanks as the lambs move into position.
Official Guidance
For official guidance on sheep welfare during lambing, refer to the GOV.UK Code of Recommendations for the Welfare of Livestock: Sheep.